How to identify and resolve MIME encoding issues in List-Unsubscribe headers?
Summary
What email marketers say9Marketer opinions
Email marketer from Elastic Email explains that using UTF-8 encoding helps prevent MIME issues. They suggest making sure your content and email settings are set up to support UTF-8 from start to finish for best results.
Email marketer from Email Deliverability Blog advises checking the encoding settings of your email sending platform. Ensure that the platform is configured to use UTF-8 encoding to prevent MIME encoding issues in headers.
Email marketer from Super User suggests that using online tools like those found on websites that offer email utilities can quickly decode MIME encoded headers for analysis and troubleshooting.
Email marketer from Litmus explains that different email clients handle MIME encoding differently. Some clients may automatically decode MIME encoded headers, while others may display the encoded text directly. Testing emails across multiple clients is essential.
Email marketer from Reddit suggests using online MIME decoder tools to quickly decode the subject line if you only need to read the subject once. If it's a frequent problem, they recommend implementing a decoding function in your email processing code.
Email marketer from Email on Acid explains that tools are available which can show you exactly what your headers will look like in different email clients - often highlighting errors in encoding.
Email marketer from Stack Overflow shares a Python snippet using `email.header.decode_header` to decode a MIME encoded header, iterates through the parts, and converts them to UTF-8 if necessary, providing a clean, readable string.
Email marketer from Mailjet notes that incorrect character set declarations are a common cause of MIME encoding issues. Ensure that the character set declared in the header matches the actual encoding of the text.
Email marketer from Server Fault explains that MIME encoding in headers typically starts with '=?', followed by the character set, encoding type (Q or B), the encoded data, and ends with '?='. The presence of these markers indicates that the header value is MIME encoded.
What the experts say5Expert opinions
Expert from Email Geeks states that List-Unsubscribe and List-Unsubscribe-Post must be covered by a DKIM signature to comply with RFC 8058.
Expert from Spam Resource explains that to ensure proper handling of List-Unsubscribe headers, it's crucial to adhere to RFC standards, particularly when implementing MIME encoding. Ensure that the encoding is correctly applied and that email clients can properly decode the header.
Expert from Email Geeks explains that if the List-Unsubscribe header starts with '=?us-ascii?Q?=3C', the platform is converting the field to MIME, which it shouldn't do. It should start with 'mailto:'.
Expert from Email Geeks shares that Gmail lies about headers and silently MIME decodes them even in 'Show Original'.
Expert from Word to the Wise explains that Gmail sometimes does not show the true headers of the email. It can pre-decode the MIME even on 'Show Original' which can hide underlying issues in the headers.
What the documentation says5Technical articles
Documentation from RFC Editor details the rules for using encoded-words in message headers, including restrictions on where they can appear and how they must be structured. It also describes the 'Q' and 'B' encoding schemes.
Documentation from GNU answers states that GNU provides tools such as 'iconv' for character set conversion. This tool can be used to convert text from one encoding to another, which can be helpful in resolving MIME encoding issues.
Documentation from RFC Editor specifies that MIME header fields can be encoded to represent characters outside the US-ASCII range using 'encoded-words'. Encoded-words are delimited by '=?' and '?=', and include the character set, encoding scheme (Q or B), and encoded text.
Documentation from IETF recommends encoding international characters in email headers using MIME to ensure proper display across different email clients and systems. This involves specifying the character set and encoding type.
Documentation from Python's email package explains that the `email.header` module provides functions to decode MIME encoded headers. Functions like `decode_header` can split a header into decoded text and charset tuples.